7
Некоторые свойства SNPs Comprise the ~90% of human genetic variation Occur with an average density ~1/1000 bp Transition CT(GA) occurs at ~2/3 of all cases, three transversions CA (GT), CG(GC), TA(AT) in ~1/6 of all cases each Most of them (~85%) are common to all populations (with differing allele frequencies)

18
Why polymorphisms are maintained in the population? Selectionists: because heterozygotes have higher fitness Neutralists: because all observed polymoprhisms are selectively neutral Reality: is always somewhat more complicated

21
Some common nsSNPs are known to affect critical structure features Frequency of the haemochromatosis allelic variant of HLA-H protein Cys260Tyr (with destroyed disulphide bond) is up to 6% in Northern Europe

45
Polyphenism : the ability of a single genome to produce two or more alternative morphologies within a single population in response to an environmental cue (such as temperature, photoperiod, or nutrition). [ Dr. Ehab Abouheif, McGill University, Montréal Québec ] The seasonal morphs of the buckeye butterfly, Precis coenia ( Nymphalidae ). The ventral surfaces are shown. The Summer morph ("linea") is on the left; the Fall morph ("rosa") is on the right. [ Scott F.Gilbert, A Companion to Developmental Biology. Chapter 22, Seasonal Polyphenism in Butterfly Wings ]

46
Damaging nsSNPs We estimate that ~20% of non-synonymous cSNPs from databases are damaging Average allele frequency of non-synonymous cSNPs predicted to be damaging is twice lower than for benign non-synonymous cSNPs We propose to use these predictions for prioritisation of candidates for association studies